A study into the genetic heritage of Orcadian men in 2000/2001 confirmed a distinctly Scandinavian influence, with the make-up of their Y-chromosomes very similar to that of modern Norwegians.

The results of DNA analysis of male volunteers from Orkney – carried out in connection with the BBC Television programme Blood of the Vikings – showed that vikings not only settled in Orkney, but also inter-married with local women that their Y-chromosomes – passed from father to son – supplanted those of the indigenous population.

The announcement that 60 per cent of the Northern Isles’ male population had Norse ancestry came as no surprise to Orcadians.

A team of geneticists from University College, London, led by Professor David Goldstein, were looking for evidence of Viking blood in the people of the British Isles.

DNA samples from mouth swabs were gathered from over 2,000 men across Britain, Ireland and Scandinavia who could trace their male line back at least three generations in the same area.

The tests looked at the Y-chromosome, which is carried only by men and passed, practically unchanged, from father to son.

First, the team studied the Y-chromosome of Scandinavian males to identify distinct genetic markers, which they could then look for in their British samples.

Shetland, Orkney and the area around Durness on the Scottish mainland were found to have the strongest Viking genetic heritage in Britain, with around 60 per cent of the male population having DNA of Norwegian origin. The remainder of the area’s population was identified as similar to the Ancient Britons, with no evidence of Anglo-Saxon or Danish influences.

In comparison, about 30 per cent of the population of the Outer Hebrides, another Viking outpost, show traces of Norwegian blood.

So the distribution of Y chromosome types in Orkney was intermediate between “Celtic areas” of Britain and Norway, indicating a shared ancestry with both populations.

The survey results mirrored historical and archaeological records, which document the Vikings’ route from Norway across to the Northern Isles, before heading down the Scottish west coast and into the Irish Sea.

At the same time, a special study carried out by an Orcadian member of the genetics team, Jim Wilson, took a closer look at Orkney’s genetic heritage.

Conscious of the fact that after Orkney was handed over to Scotland in 1469, immigrants from mainland Britain had settled in the islands, Jim Wilson’s study focused on a group of subjects with Orcadian surnames which dated back to the end of the Earldom.

He discovered that, in this group, as would be expected, the proportion of Norwegian Y chromosomes increased.

But what does all this mean?

Does it show, one way or another, how the Norse took Orkney? Unfortunately not.

Although it could be argued that the massive influx of Norwegian male genetic markers could be indicative of the wiping out of the native male population, it could also have been a gradual process, over a number of centuries.

In the same way, the results could suggest a level of inter-breeding between Pict and Viking. But this might have happened at any time after the initial Nose takeover of the islands.

Published in the journal Heredity, the study was carried out by Dr Sara Goodacre, from the University of East Anglia, with colleagues in Oxford and Iceland. As well as looking again at the paternally-inherited Y chromosome, this project was investigating mitochondrial DNA (mtDNA), which is passed from mother to daughter.

It revealed that equal proportions of Scandinavian males and females settled in Orkney, which they found to have an overall Scandinavian ancestry of approximately 30.

This contrasted the situation for the Western Isles, where the overall Scandinavian ancestry was less (approximately 15%) and where there was a disproportionately high contribution from Scandinavian males.

These results suggested Orkney and Shetland, areas close to Norway, might have been settled primarily by Scandinavian family groups. Further away, there seems to have been more incidents of lone Viking males, who later established families with local wives.